Wheel bracket mechanism for an electric wheelchair equipped with auxiliary wheels

ABSTRACT

A wheel bracket mechanism for an electric wheelchair equipped with auxiliary wheels, which comprises a frame, a pair of driver wheel brackets, four pedestal assemblies, a pair of caster brackets, a pair of oscillating assembly and a pair of anti-tipping brackets. The frame is provide with a pair of castor brackets at the front end and a pair of anti-tipping brackets at the rear end thereof, a pair of driver wheel brackets are secured to the frame with a front end stretching ahead of it and located between the castor brackets and the anti-tipping brackets, and between the castor brackets and the driver wheel bracket disposed an oscillating assemblies, four pedestal assemblies equipped with cushioning blocks are disposed at both sides of the front and rear end of the frame respectively in pairs with located opposite to each other.

BACK GROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates a wheel bracket mechanism for anelectric wheelchair, and more particularly to a wheel bracket mechanismfor an electric wheelchair equipped with auxiliary wheels. Descriptionof the Prior Arts Electric wheelchairs or the like have become anindispensable means of transport to the ailing old or the handicapped,including indoor and out activities, traveling and boarding on theairplane, and so on.

[0003] A wheel bracket mechanism of a conventional electric wheelchair(and transport means or the like) is normally rectangularformed as shownin FIGS. 1-2. Those are common drawings in accordance with the U.S. Pat.Nos. 5,944,131 and 6,199,647 B1. Both of which disclosed a rectangularframe 10 is provided with driver wheel brackets 11 for drive wheels 111secured thereon, the same further provided with a plurality of frontauxiliary brackets 12 disposed at the sides of the front end and rearend respectively for auxiliary wheels secured thereon correspondingly.The front auxiliary brackets 12 and the driver wheel brackets 11 aresecured on the rectangular frame 10 meanwhile additionally supported byauxiliary wheel springs 13 and driver wheel springs 14 respectively. Bythe arrangements of the auxiliary wheel springs 13 and the driver wheelsprings 14, the front auxiliary brackets 12 and the driver wheelbrackets 11 may be permitted to extend or contract upon a bump, suchgive rise to a cushioning effect in case of riding up and down a slopeor on the uneven roads. Although this conventional wheel chair has themain functions of a wheelchair, there are still some disadvantages needsto be overcome as stability, safety and comfortableness are concerned:

[0004] First, in terms of stability, the conventional rectangular frame10 just takes advantage of the longitudinal expansion and compression ofthe front auxiliary wheel springs 13 and the driver wheel springs 14 tomaintain the stability. Although the elastic forces of the two mentionedsprings may force the front auxiliary bracket 12 and the driver wheelbracket 11 back to the predetermined position, the same may also causevibrations of the rectangular frame 10 up and down. Moreover, the frontauxiliary brackets 12 are suspended a bit over the ground by virtue ofthe auxiliary wheel springs 13 (as shown in FIG. 1) which only can beused in case of ridding up and down a slope (as shown in FIG. 2). Suchan unstable electric wheelchair with front wheels over-suspended is notable to provide a comfortable driving to the occupants, especially tothe old patients.

[0005] Second, in terms of security, although the conventionalrectangular frame 10 is allowed to effect expansion and compression ofthe driver wheel 111 and auxiliary wheel 121 by virtue of the auxiliarywheel spring 13 and the driver wheel spring 14. However, the compressionand expansion of the front auxiliary bracket 12 and the driver wheelbracket 11 is performed independently and individually due to nocoordinating device disposed therebetween, further including the factorsthat the rear auxiliary brackets are incompressible and the frontauxiliary brackets 12 are a bit suspended over the ground. Thereby theconventional rectangular frame 10 may be tilted and swayed duringridding, and the center of gravity of the wheelchair moves back andforth substantially. Such that increased the possibility of tipping,which is absolutely unfit for the old and handicapped riding.

[0006] Third, in terms of comfortableness, the current market ofelectric wheel chair is a keen competition and the comfortable riddinghas become an indispensable prerequisite of the consumers. However, thestability of the conventional rectangular frame 10 is still far fromideal, so the comfortableness becomes the major topic for the producers'study at present.

[0007] The present invention has arisen to mitigate and/or obviate theafore-described disadvantages of the conventional electric wheelchair.

SUMMARY OF THE INVENTION

[0008] In accordance with one aspect of the present invention, there isprovided with a wheel bracket mechanism for an electric wheelchairequipped with auxiliary wheels, which comprises a frame, a pair ofdriver wheel brackets, four pedestal assemblies, a pair of casterbrackets, a pair of oscillating assembly and a pair of anti-tippingbrackets. The frame is provided with a pair of castor brackets at thefront end and a pair of anti-tipping brackets at the rear endrespectively, a pair of driver wheel brackets are secured to the framewith a front end stretching ahead thereof and located between the castorbrackets and the anti-tipping brackets, and between the castor bracketsand the driver wheel bracket disposed an oscillating assemblies, fourpedestal assemblies equipped with cushioning blocks are disposed at bothsides of the front and rear end of the frame respectively in pairs withlocated opposite to each other.

[0009] The primary objective of the present invention is to provide awheel bracket mechanism for an electric wheelchair, which provides astable support to the frame by virtue of the pedestal assemblies.Furthermore, an oscillating assembly disposed between the castor wheelbrackets and the driver wheel brackets, such that, by virtue of thecoordination of the three, the wheelchair is able to automaticallyadjust the castor wheel brackets and the driver wheel brackets by itselfin case of riding up and/or down a slope. Thereby the electricwheelchair of the present invention is capable of providing a safe andstable ridding according to different slopes.

[0010] The further objective of the present invention is to provide awheel bracket mechanism for an electric wheelchair provided with aplurality of pedestal assemblies equipped with cushioning block, theexpansion and compression of the pedestal assemblies possess is muchsmooth and stable than that of spring, no elastic shake will be caused.By such an arrangement, the stability of the wheelchair of the presentinvention is better than that of the conventional one.

[0011] The present invention will become more obvious from the followingdescription when taken in connection with the accompanying drawings,which shows, for purpose of illustrations only, the preferredembodiments in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a schematic plan view of a conventional wheelchairridding on the plane ground;

[0013]FIG. 2 is a schematic plan view of the conventional wheelchairridding down a slope;

[0014]FIG. 3 is an exploded view of a wheel bracket mechanism of anelectric wheelchair in accordance with the present invention;

[0015]FIG. 4 is a side view of the wheel bracket mechanism of anelectric wheelchair in accordance with the present invention;

[0016]FIG. 5 is a schematic plan view of showing the wheel bracketmechanism of an electric wheelchair in accordance with the presentinvention is ridding up a slope;

[0017]FIG. 6 is a schematic plan view of showing the wheel bracketmechanism of an electric wheelchair in accordance with the presentinvention is ridding down a slope.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0018] Referring to FIGS. 3-4, wherein, in accordance with the presentinvention, a wheel bracket mechanism for an electric wheelchair equippedwith auxiliary wheels is shown and generally comprises a frame 20, apair of driver wheel brackets 30, four pedestal assemblies 40, a pair ofcastor brackets 50, a pair of oscillating assembly 60 and a pair ofanti-tipping brackets 70.

[0019] The frame 20 in shape of rectangle is provided with two earmembers 21 at both sides with symmetrical to each other and locatedbetween the front and rear end. Each of the ear members has an aperture211 defined thereof.

[0020] The driver wheel bracket 30 is crank-like configured, at the rearend of which is secured a motor 31 and drive shaft 32 respectively. Thedrive shaft 32 serves to drive the driver wheel 321. At the middle ofthe driver wheel bracket 30 is provided with a hole 33 whichcorresponding to an aperture 211 of the ear member 21 of the frame 20,and by an axle 34 inserting through the hole 33 and the aperture 211 ofthe ear member 21. Moreover, the front end of the driver wheel bracket30 stretches ahead of the frame 20 and at the front portion of which isdefined with an aperture 35.

[0021] The pedestal assemblies 40 each consists of a tube 41 and aplurality of cushion blocks 42. The tubes 41 are disposed at both sidesof the front and rear end of the frame 20 respectively in pairs withlocated opposite to each other. The cushion blocks 42 disposed in innersides of the corresponding tube 42 and defined a space 43 squared incross section.

[0022] The castor brackets 50 is each provided with a castor 511 securedto a strut 51 at the front end and a rod 52 squared in cross sectionvertically disposed at the rear end thereof. The rod 52 having athreaded hole 521 defined at the end and to be received in thecorresponding spaces 43 of the pedestal assemblies 40 (the two pedestalassemblies 40 mentioned above are located at the front end of the frame20) and with covering member 522 screwing in the threaded hole 521.Furthermore, an aperture 53 is defined in the castor bracket 50 adjacentto the strut 51, where corresponding to the location of the aperture 35of the driver wheel bracket 30.

[0023] The oscillating assembly 60 consists of a pair of plates 61, arolling shaft 62 and a roller 63. The plates 61 is each provided with astripe aperture 611, each of plates 61 is engaged with the aperture 35of the drive wheel bracket 30 and the aperture 53 of the castor bracket50 via the top and bottom of the aperture 611 respectively by virtue ofa pair of bolts 64 and screw nuts 65. The roller 63 mounted onto therolling shaft 62, then the rolling shaft 62 is disposed in the middle ofthe stripe aperture 611 of the plates 61 by virtue of a screw nut 65.

[0024] The anti-tipping brackets 70 is each provided with ananti-tipping wheel 711 secured to a strut 71 at the front end and a rod72 squared in cross section vertically disposed at the rear end thereof.The rod 72 including a threaded hole 721 defined at the end and to bereceived in the corresponding spaces 43 of the pedestal assemblies 40(the two pedestal assemblies 40 mentioned above are located at the rearend of the frame 20) and with covering member 722 screwing in thethreaded hole 721.

[0025] In operation with referring to FIG. 5, which shows a wheelchairof the present invention is riding on a slope. The castor 511 of thecastor wheel bracket 50 locates at a relatively higher level of theslope and being under an upright pressure. Accordingly, the squared rod52 pushes the majority of the cushioning blocks 42 in the correspondingpedestal assemblies 40 (the cushioning blocks 42 are deformed and startto store energy) and causes a slight clockwise spin of the castor wheelbracket 50 (as indicated in FIG. 5). While the driver wheel bracket 30is not pressed, so the pair of the plates 61 of the oscillating assembly60 starts to the spin counterclockwise. Meanwhile, with the spin of theplates 61 together with roller 63 and the stripe aperture 611, thepressure is transmitted to the front end of the driver wheel bracket 30.And the rear portion of the driver wheel 321 of the driver wheel bracket30 will take part of the pressure from the castor 511 (clockwise force)by virtue of the axel 34 of the drive wheel bracket 30 together with theaperture 211 of the ear member 21. Such that the ascension of the castorbracket 511 will not cause an upright inclination of the front end ofthe frame 20, but cooperating with the driver wheel 321 of the driverwheel bracket 30 to raise the frame 20 steadily. Thereby, in case ofridding up a slope, the castor wheel bracket 50 and the driver wheelbracket 30 will slightly spin clockwise, and the frame 20 will slightlyraise up in steady without inclined as conventional frame do.

[0026] Until the roller 63 running to other side, which indicates thatthe ascension of the castor bracket 50 is great (the upward slope issteep), the pressure of the castor 511 will be more preciselytransmitted to the driver wheel bracket 30 (the castor bracket 50 andthe driver wheel bracket 30 acting as a whole). Thereby, the wheelchairof the present invention is able to adjust itself automatically inaccordance with different upward slopes.

[0027] Referring now to FIG. 6, which shows a wheel chair of the presentinvention is riding down a slope. The castor 511 of the castor wheelbracket 50 locates at a relatively lower level of the slope.Accordingly, the squared rod 52 pushes the majority of the cushioningblocks 42 in the corresponding pedestal assemblies 40 (the cushioningblocks 42 are deformed and start to store energy) and causes a slightcounterclockwise spin of the castor wheel bracket 50 (as indicated inFIG.6). While the driver wheel bracket 30 is not pressed, so the pair ofthe plates 61 of the oscillating assembly 60 starts to the spinclockwise. Meanwhile, with the spin of the plates 61 together withroller 63 and the stripe aperture 611, the pressure is transmitted tothe front end of the driver wheel bracket 30. And the rear portion ofthe driver wheel 321 of the driver wheel bracket 30 will take part ofthe pressure from the castor 511 (counterclockwise force) by virtue ofthe axel 34 of the drive wheel bracket 30 together with the aperture 211of the ear member 21. Such that the descent of the castor bracket 511will not cause an downward inclination of the front end of the frame 20,but cooperating with the driver wheel 321 of the driver wheel bracket 30to descend the frame 20 steadily. Thereby, in case of ridding down aslope, the castor wheel bracket 50 and the driver wheel bracket 30 willslightly spin counterclockwise, and the frame 20 will slightly descendin steady without inclined as conventional frame do.

[0028] Until the castor bracket 50 and the driver wheel bracket 30moving to both sides of the roller 63, which indicates that the descentof the castor bracket 50 is great (the downward slope is steep), thepressure of the castor 511 will be more precisely transmitted to thedriver wheel bracket 30 by virtue of the roller 63 (the castor bracket50 and the driver wheel bracket 30 acting as a whole). Thereby, thewheelchair of the present invention is able to adjust itselfautomatically in accordance with different downward slopes.

[0029] It will be noted that due to the anti-tipping brackets 70 arealso provided with pedestal assemblies 40, the majority of thecushioning blocks 42 in the pedestal assemblies 40 will alike play arole in assisting the ascension and descent of the frame 20 so as toprovide a smooth, safe and comfortable riding. In addition, thelatitudinal expansion and compression of the pedestal assemblies 40 isactuated by the restoring force of the cushioning blocks 42, and therestoring force of the cushioning blocks 42 is only limited forrecovering the deformation of it and will not be over great. Thereby,which will generate a smooth latitudinal expansion and compression ofthe pedestal assemblies 40.

[0030] It should be clear to those skilled in the art that furtherembodiments may be made without departing from the scope of the presentinvention.

What is claimed is:
 1. A wheel bracket mechanism for an electricwheelchair equipped with auxiliary wheels comprising: a frame, a pair ofdriver wheel brackets, four pedestal assemblies, a pair of casterbrackets, a pair of oscillating assembly and a pair of anti-tippingbrackets; wherein: the frame in shape of rectangle each having anaperture at both sides with symmetrical to each other and locatedbetween the front and rear end; the driver wheel brackets provided witha motor and drive shaft secured at the rear end respectively, the driverwheel brackets secured to the frame via the aperture of it with a frontend stretching ahead, an aperture formed at the front end of the eachdriver wheel brackets; the pedestal assemblies disposed at both sides ofthe front and rear end of the frame; the castor brackets each providedwith a castor secured to a strut at the front end and a rod disposed atthe rear end thereof, the rods received in the pedestal assembliesrespectively, an aperture defined adjacent to the strut in the castorbracket with corresponding to the location of the aperture of the driverwheel bracket; the oscillating assembly consisting of a pair of plates,a rolling shaft and a roller, the plates each provided with a stripeaperture, each of plates engaged with the aperture of the driver wheelbracket and the aperture of the castor bracket via the top and bottom ofthe stripe aperture respectively, the roller mounted onto the rollingshaft, then the rolling shaft movably disposed in the middle of thestripe aperture of the plates; the anti-tipping bracket each providedwith an anti-tipping wheel at the front end and a rod disposed at therear end thereof, the rod received in the corresponding pedestalassemblies.
 2. The wheel bracket mechanism for an electric wheelchairequipped with auxiliary wheels as claimed in claim 1, wherein thepedestal assemblies each consist of a tube and a plurality of cushionblocks, the tubes are disposed at both sides of the front and rear endof the frame respectively in pairs with locating opposite to each other,the cushion blocks are disposed in inner sides of the corresponding tubeand defining a symmetric space, every rod of the castor brackets and theanti-tipping brackets has a threaded hole defined at the end and servedto be received in the corresponding symmetric spaces of the pedestalassemblies, and with a covering member is fixed in the threaded hole. 3.The wheel bracket mechanism for an electric wheelchair equipped withauxiliary wheels as claimed in claim 2, wherein the cushioning blocks inthe pedestal assembly define a symmetric space squared in cross section,every rod of the castor brackets and the anti-tipping brackets issymmetric formed with squared in cross section.
 4. The wheel bracketmechanism for an electric wheelchair equipped with auxiliary wheels asclaimed in claim 1, wherein the driver wheel bracket is crank-likeconfigured.